the fun this about those errors is it already say's what's wrong.
don't freak out if you see something like this but read something and see if you can find something which you might understand. in this case you see at the end of the first line and the 2nd line what's wrong in proper english.
Login failed for user 'sa'. The user is not associated with a trusted sql server connection.
well search for it on google and you'll get a huge amount of hits.
like

one which is the first it's from microsoft it tells exactly how to solve it well sometimes it might be a bit cryptic if you don't know what all those things mean but you still have hunderds of other site's left.
so I click at another website

one.
and tada that's your problem and it has a more detailed explainment about solving it.